chore(controller): update djangorestframework to 2.3.14

Several months of cleanup and bug fixes to a core Deis library:
https://github.com/tomchristie/django-rest-framework/compare/2.3.13...2.3.14
Merge pull request #1586 from mboersma/update-django-rest

chore(controller): update djangorestframework to 2.3.14